The present invention relates to surgical endoscopes and more particularly to endoscopes for use in minimally invasive surgery. Minimally invasive surgery is performed through a primary incision that is smaller than most traditional surgical openings. Such surgery relies on an endoscope for visualization of the operative field. A surgeon can insert the endoscope into a patient's body via the primary incision or via an alternative insertion point.
An endoscope includes any instrument inserted into the body to obtain a view of the interior of the body. However, an endoscope for minimally invasive surgery often includes a long, thin imaging assembly with an image detecting element located at the distal end of the assembly and electrically conductive leads extending from the image detecting element. Such endoscopes generally also include an illumination fiber bundle which brings light down to the region of the imaging or camera lens and which illuminates the field of view. An endoscope system for minimally invasive surgery will often display a video image on a large monitor.
Generally for thoracoscopic surgery, the viewing endoscope is handled and operated by a dedicated operating room assistant. The endoscope can have a short focal length and working distance allowing the operator to position the endoscope close to a surgical field when the surgeon makes incisions for harvesting a small vessel or when the surgeon removes a tissue specimen.
Thoracic endoscopes generally have a series of small diameter lenses, e.g., rod lenses, adapted to relay an image from an objective assembly to an eyepiece. Alternatively, thoracic endoscopes can have an objective which directly images onto a CCD element or video pick-up under about one centimeter in cross dimension. The optics may have a field of view between about 50.degree. to over 100.degree., and a working distance generally on the order of one half to two inches. These specifications allow the camera to be sufficiently close to the surgical instrument to effectively image the details of the surgical field.
One drawback of a typical endoscope with a field of view of about 50.degree. is that to obtain a sufficiently enlarged view of the surgical field so as to facilitate surgical tasks such as dissecting and suturing tissue, clipping vessels, and the like, the endoscope must be moved closer to the tissue and constantly re-positioned as the surgery proceeds. Advancing the endoscope narrows the actual view. In addition, when operating at a working distance of about one inch, the surgeon may have a distorted or partially obscured view of even a simple structure, such as a vessel or small nodule, or may lose track of where in the operating theater he is actually performing. It is then necessary to retract the endoscope to obtain a wider field of view.
In thoracoscopic surgery, it is important for the surgeon to have access to a wide field of view of the surgical field because a typical procedure can involve cutting into the chest wall to harvest one or more blood vessels, for example when performing cardiac bypass grafting. The chest cavity includes organs such as a patient's heart and lungs and numerous vascular structures. These organs and vascular structures can obstruct endoscopes with a narrow field of view. In some cases a surgeon inserts her fingertips through the primary incision. The surgeons fingertips can also obstruct the endoscopes view of the surgical field.
In addition, a wide field of view can be necessary, for example, to guide a surgical instrument to a surgical site when the instrument is inserted at a point remote from the endoscope insertion point. A surgeon can accomplish such a wide field of view by positioning the endoscope at an appropriate angle far enough from the surgical site and far enough from the instrument insertion point to bring both the surgical site and the instrument insertion point into its field of view.
A supplemental view can also be obtained by inserting a second endoscope through a second endoscope insertion point to view the surgical arena from a different vantage point or angle, or with different overall magnification or field of view. The manipulation of the second endoscope would then require care 1) to determine and to maintain the endoscope's position, 2) to keep the surgical site in the field of view, and 3) to correlate the site shown in one endoscope with the site imaged by the other. This manipulation is difficult because of the number of instruments and incisions already involved in an operation and the limited visibility of the surgical field due to the intervening structures present when performing a surgical intervention, such as a resection or the excavation of a vessel.
A number of devices or systems for obtaining adequate views have been previously proposed to address related problems in the field of laparoscopic or bronchoscopic surgery or endoscopic biopsies. Thus, endoscope system designers have proposed various arrangements of multiple imaging sites and corresponding video synchronization, or screen-within-a-screen processing for situations where operators insert an endoscope along a body passage and use the endoscope for mapping or viewing features on the passage.
However, the situation of viewing polyps in the colon, or other features within a tubular passage differs substantially from the problem posed by imaging a surgical arena in a relatively large body cavity, such as the chest cavity. In thoracoscopic procedures, for example, instruments are inserted and tissue excavation or resection is carried out in and around a variety of tissues, mobile or moving organs, or the surgeon's fingers. In the latter context, there is no natural channel guiding the endoscope. The extent of the operating arena may be quite large and include a number of occluding structures around the surgical site itself.
Furthermore, in many procedures, it is common to use several distinct endoscopes. For example, in thoracoscopy, a surgeon will often initiate a procedure using a flexible endoscope. The flexible endoscope blocks the left or right bronchus allowing greater visualization of the surgical field. Such a flexible endoscope typically costs between about $8,000 and about $12,000. Following this initiation of the procedure, a rigid endoscope is used for thoracoscopic examination of the thoracic cavity. Such a rigid endoscope typically costs between about $3,000 and about $5,000. In addition, a surgeon can require an articulating endoscope or a different optical angle scope. An articulating scope typically costs between about $3,000 and about $5,000.
Another drawback of present endoscope systems is the amount of light lost in the illumination fiber bundle. Typical illumination fiber bundles deliver approximately 40% of the light delivered to the bundle by the light source. Inefficient transmission of light from the light source by the illumination fiber bundle can limit the imaging capability of an endoscope.
Thus there remains a need for improvement in endoscopic systems for surgical use.
Accordingly it is an object of the present invention to provide an endoscope system configured for effective viewing in and around a variety of tissues, mobile or moving organs, and the surgeon's fingers.
It is a further object of the invention to provide an endoscope system that does not require multiple, expensive endoscopes to successfully and efficiently complete a surgical procedure.
It is another object of the invention to minimize light loss in an illumination fiber bundle.
Other objects of the invention will in part be obvious and will in part appear hereinafter.